Characterizing the phase profile of a vortex beam with angular-double-slit interference.

The diffracted intensity distribution of a Laguerre–Gaussian beam is studied with an angular-double-slit interferometer. We experimentally demonstrate that the spiral phase structure of a vortex beam can be clearly revealed in this interference geometry, and it gives us an efficient way to distinguish different orders of Laguerre–Gaussian beams. This angular-double-slit interferometer gives us a better understanding of the phase structure of a vortex beam and the interference phenomenon of vortex beams. [ABSTRACT FROM AUTHOR]